Systems and methods for vascular filter retrieval

ABSTRACT

Apparatus and methods for retrieving a vascular filter from a vessel are provided wherein a retrieval adapter is delivered to a treatment site concurrently along with an interventional device to reduce the number of steps required to remove the vascular filter. The retrieval adapter also reduces the possibility of entangling the vascular filter with a stent disposed within the vessel during removal of the vascular filter. A separate retrieval catheter is also described for use in conjunction with the retrieval adapter.

FIELD OF THE INVENTION

[0001] The present invention relates to apparatus and methods forretrieving a vascular device, such as a filter, from within a vessel.More particularly, the present invention provides apparatus useful forretrieving a vascular filter used to prevent embolization associatedwith diagnostic or therapeutic interventional procedures, thrombectomyand embolectomy.

BACKGROUND OF THE INVENTION

[0002] Percutaneous interventional procedures to treat occlusivevascular disease, such as angioplasty, atherectomy, and stenting, oftendislodge material from the vessel walls. This dislodged material, knownas emboli, enters the bloodstream and may be large enough to occludesmaller downstream vessels, potentially blocking blood flow to tissue.The resulting ischemia poses a serious threat to the health or life of apatient if the blockage occurs in critical tissue, such as the heart,lungs, or brain.

[0003] The deployment of stents and stent-grafts to treat vasculardisease, such as aneurysms, involves the introduction of foreign objectsinto the bloodstream, and also may result in the formation of clots orrelease of emboli. Such particulate matter, if released into thebloodstream, also may cause infarction or stroke.

[0004] Numerous blood filters are known that are designed to capturematerial liberated from vessel walls during the treatment of vasculardisease. Such treatment procedures, such as angioplasty, atherectomy andstenting, typically involve transluminally inserting an interventionaldevice to the treatment site along a guidewire. Upon completion of theprocedure, the interventional device is removed from the patient's bloodvessel, and a retrieval mechanism, such as a sheath, is advanced alongthe guidewire in order to retrieve the blood filter.

[0005] One drawback associated with using a sheath to retrieve a filteris that the retrieval process requires two steps: (1) the interventionaldevice (e.g., angioplasty catheter) must be removed and (2) theretrieval sheath must then be advanced along the guidewire to retrievethe filter. This additional exchange adds time to the length of theprocedure, involves introduction of an additional element (the retrievalcatheter) into the patient's vasculature, and enhances the risk ofdislodging the filter and permitting emboli to escape therefrom.

[0006] Moreover, as the retrieval sheath is advanced along theguidewire, its distal end may become entangled with a stent disposedwithin the patient's vessel. If, for example, a stent has been deployed,the distal end of the retrieval sheath may inadvertently engage a stentstrut, preventing further advancement of the retrieval sheath within thevessel, or even possibly causing vessel dissection.

[0007] One disadvantage associated with attempting to retrieve avascular filter using the guidewire lumen of an interventional device,such as an angioplasty catheter, is that the diameters of such lumensare typically quite small, e.g., 0.014 inch. Accordingly, it is notpossible to retrieve previously known vascular filters using theguidewire lumens of most interventional devices.

[0008] In view of the foregoing, it would be desirable to provideimproved apparatus and methods that streamline retrieval of a vascularfilter.

[0009] It further would be desirable to provide improved apparatus andmethods that facilitate retrieval of a vascular filter, with reducedrisk of entangling a retrieval sheath in a deployed stent.

SUMMARY OF THE INVENTION

[0010] In view of the foregoing, it is an object of the presentinvention to provide improved apparatus and methods that streamlineretrieval of a vascular filter.

[0011] It is another object of the present invention to provide improvedapparatus and methods that facilitate retrieval of a vascular filter,with reduced risk of entangling a retrieval sheath in a deployed stent.

[0012] These and other objects of the present invention are accomplishedby providing a retrieval apparatus that reduces the time and effortrequired to retrieve a vascular filter from a patient's vessel.

[0013] In one preferred embodiment, the present invention includes aretrieval adapter having a proximal end configured to be fitted to theend of an interventional device, such as an angioplasty catheter, and aradially expandable distal end. Upon completion of an interventionalprocedure such as angioplasty, the balloon of the angioplasty catheteris deflated and the angioplasty catheter then is advanced along theguidewire until the adapter captures the vascular filter.

[0014] Alternatively, upon completion of the interventional procedure,the guidewire and attached vascular filter may be withdrawn proximallyuntil the vascular filter engages and is caused to be collapsed by theadapter. Once the vascular filter is collapsed, the vascular filter ispartially withdrawn within the adapter, and the vascular filter,adapter, interventional device and guidewire are all removed from thevessel. This streamlined procedure provides a substantial improvementover previously known systems, which typically require exchanging theinterventional device for a retrieval sheath before retrieving thevascular filter from the treatment site.

[0015] In another embodiment, the retrieval adapter of the presentinvention may be loaded directly onto the guidewire having the vascularfilter so that the adapter is delivered to a treatment site concurrentlywith the filter. After completion of a diagnostic or therapeuticprocedure involving an interventional device, such as an angioplastycatheter, the interventional device is advanced along the guidewire. Asthe distal end of the interventional device moves distally, it abutsagainst the adapter and urges the adapter into contact with the filter,thereby causing the adapter to collapse and capture the vascular filter.Alternatively, as for the previous embodiment, the interventional devicemay be held stationary and the vascular filter and adapter retractedproximally.

[0016] In yet another embodiment, the present invention includes aretrieval catheter having proximal and distal ends. The proximal end ofthe catheter is loaded onto the distal end of an interventional device,and that assemblage then is loaded onto the guidewire having thevascular filter. After completion of a diagnostic or therapeuticprocedure, such as stent deployment, the retrieval catheter is advancedover the working element of the interventional device (e.g., thedeflated balloon) and the vascular filter. Alternatively, the retrievalcatheter may be held stationary and the vascular filter and guidewireretracted proximally to collapse and capture the filter in the retrievalsheath.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects and advantages of the presentinvention will be apparent upon consideration of the following detaileddescription, taken in conjunction with the accompanying drawings, inwhich like reference characters refer to like parts throughout, and inwhich:

[0018]FIG. 1 is a perspective view of a first previously known vascularfilter suitable for use with the apparatus of the present invention;

[0019]FIG. 2 is a perspective view of another previously known vascularfilter suitable for use with the apparatus of the present invention;

[0020]FIG. 3 is a side view of yet another vascular filter suitable foruse with the apparatus of the present invention;

[0021]FIGS. 4A and 4B are, respectively, side sectional and side viewsof apparatus of the present invention;

[0022]FIGS. 5A and 5B are side sectional views illustrating the use ofthe apparatus of FIGS. 4 to retrieve the vascular filter of FIG. 3;

[0023]FIG. 6 is a side view of a retrieval catheter constructed inaccordance with the principles of the present invention;

[0024] FIGS. 7A-7C are side sectional views depicting a method ofretrieving the vascular filter of FIG. 3 using the retrieval catheter ofFIG. 6 in conjunction with the apparatus of FIGS. 4;

[0025] FIGS. 8A-8B are side sectional views depicting a method ofretrieving the vascular filter of FIG. 3 using the retrieval catheter ofFIG. 6 alone;

[0026]FIG. 9 is a side sectional view of an alternative method of usingthe apparatus of FIGS. 4;

[0027]FIGS. 10A and 10B are side sectional views depicting analternative embodiment of the apparatus of FIGS. 4;

[0028]FIGS. 11A and 11B are side sectional views depicting anotheralternative embodiment of the apparatus of FIGS. 4;

[0029]FIG. 12 is a side view of a further alternative embodiment of theapparatus of FIGS. 4 incorporated into the vascular filter of FIG. 3;

[0030] FIGS. 13A-13C are side sectional views depicting a method ofusing apparatus of FIG. 12;

[0031]FIG. 14 is a side view of yet another alternative embodiment ofthe apparatus of FIGS. 4 incorporated into the vascular filter of FIG.3; and

[0032] FIGS. 15A-15C are side sectional views depicting a method ofusing apparatus of FIG. 14.

DETAILED DESCRIPTION OF THE INVENTION

[0033] The present invention is directed to apparatus and methods forclosing the mouth of a vascular filter or similar vascular device so asto prevent emboli from escaping during contraction and removal of thevascular filter or device, while reducing the number of equipmentexchanges associated with such removal.

[0034] A number of vascular filters are known for providing distalprotection against embolization in conjunction with a transluminaldiagnostic or therapeutic procedure, such as angioplasty. These filtersgenerally are deployed distal to a vascular lesion prior to undertakinga diagnostic or therapeutic procedure, and are designed to filter emboliliberated during the procedure from the patient's blood. A briefdescription of a number of these filters is provided as context foradvantages achievable using the apparatus of the present invention.

[0035]FIG. 1 shows vascular filter 10 described in U.S. Pat. No.6,129,739 to Khosravi et al., which is incorporated herein in itsentirety. Vascular filter 10 includes articulated support hoop 11carrying blood permeable sac 12. Support hoop 11 is attached to tube 13at point 14, and permits guidewire 15 to be rotated independently ofsupport hoop 11. Blood permeable sac 12 filters emboli and otherundesirable material from blood passing through the filter, whilepermitting blood cells to pass freely therethrough. When aninterventional procedure, e.g., angioplasty or stenting, is completed,vascular filter 10 is retrieved by partially withdrawing support hoop 11into the lumen of the interventional device (e.g., angioplastycatheter), and removing the catheter and vascular filter.

[0036]FIG. 2 depicts another type of vascular filter suitable for usewith the methods and apparatus of the present invention, and isdescribed in U.S. Pat. No. 6,152,946 to Broome et al., which isincorporated herein by reference. Vascular filter 20 includes aplurality of longitudinally-extending ribs 21 forming frame 22 thatsupports mouth 23. Cone-shaped filter 24 is coupled to mouth 23. Ribs 21are coupled to collar 25, which is displaced distally along guidewire 26to expand and deploy frame 22 and filter 24. Filter 24 includes holes 27that permit blood to pass through the filter, while trapping emboli.Vascular filter 20 is collapsed for retrieval by applying a load againstribs 21 that causes collar 25 to slide proximally, thereby closing thevascular filter.

[0037] Referring now to FIG. 3, another vascular filter suitable for usewith the apparatus and methods of the present invention is described.Vascular filter 30 is described in detail in co-pending, commonlyassigned U.S. patent application Ser. No. ______, filed ______ (AttorneyDocket No. EPI-002), and is summarily described here.

[0038] Vascular filter 30 preferably includes self-expanding supporthoop 31 mounted on suspension strut 32, and supports blood permeable sac33. Blood permeable sac 33 comprises a biocompatible polymeric materialhaving a multiplicity of pores. Suspension strut 32 is affixed atproximal end 34 to tube 35, and positions support hoop 31 approximatelyconcentric to tube 35 when disposed in a substantially straight lengthof vessel, but advantageously permits the support hoop to becomeeccentrically displaced relative to support tube 35 when the filter isdeployed in a curved vessel.

[0039] Distal end 36 of blood permeable sac 33 is illustratively mountedto nose cone 37, which is in turn mounted to tube 35. Filter 30 ismounted on guidewire 38 between proximal stop 39 and enlarged floppy tip40 of the guidewire, which functions as a distal stop. Tube 35 permitsguidewire 38 to rotate independently of filter 30, thereby permittingfloppy tip 40 of the guidewire to be directed within the vessel withoutcausing the blood permeable sac to become wrapped around guidewire 38.

[0040] Referring now to FIGS. 4A and 4B, apparatus constructed inaccordance with the principles of the present invention is described.Apparatus 50 of the present invention, referred to hereinafter as a“retrieval adapter,” permits a conventional interventional device, suchas an angioplasty catheter or stent delivery system, to be employed inretrieving a vascular filter of the types shown in FIGS. 1-3.

[0041] Adapter 50 preferably includes curved distal end 51 havingexpansion slits 52, opening 53, tubular body 54 having internal lumen55, and tapered proximal region 56. Optionally, adapter 50 may includehelical coil 57 embedded in wall 58 to reinforce the adapter. Adapter 50preferably is constructed of a thin biocompatible material, such aspolyethylene, polypropylene, polyurethane, polyester, polyethyleneterephthalate, nylon, polytetrafluoroethylene, or Pebax®, however, anyother suitable biocompatible material or a combination of such materialsmay be used, if desired.

[0042] Adapter 50 preferably is constructed so that it has sufficientstiffness to be urged along guidewire 59 and through curved vasculaturewithin a patient's circulatory system. Tapered proximal region 56enables adapter 50 to be coupled to a conventional interventionaldevice, such as an angioplasty catheter or stent delivery catheter.Adapter 50 has sufficient stiffness so as to not buckle or kink whenbeing urged into engagement with a previously deployed vascular filterduring filter retrieval.

[0043] Distal end 51 preferably has a smooth, rounded tip to reduce therisk of adapter 50 from catching a flap of dissected tissue or on astent deployed within a vessel. Expansion slits 52 permit the curvedportions of distal end 51 to expand to accept a vascular filter whenadapter 50 is advanced along guidewire 59, so that opening 53 at leastpartially accommodates a portion of a deployed vascular filter. Adapter50 optionally may comprise a radiopaque material, e.g., a bariumsulfate-infused (BaSO₄) polymer or by using metal markers, to permitviewing of the adapter using a fluoroscope. In addition, coil 57 alsomay comprise a radiopaque material.

[0044] Tapered region 56 is configured so that it engages the interioror exterior surface of a conventional interventional device, such as anangioplasty catheter or stent delivery system. Tapered region 56 alsoaids in disposing adapter 50 concentric with respect to guidewire 59. Inaccordance with the principles of the present invention, adapter 50 isdelivered at the same time as an interventional device to be used forthe diagnostic or therapeutic treatment. Accordingly, adapter 50provides a significant improvement over previously known filterretrieval systems, by eliminating the need for a separate catheterexchange to retrieve the vascular filter.

[0045] Optionally, adapter 50 may be bonded to the distal end of theinterventional device using a standard biocompatible adhesive, pressfitting, or other suitable means. For example, the internal surface oflumen 55 at tapered proximal end 56 may be coated with apressure-sensitive adhesive. A clinician may then couple adapter 50 tothe distal end of an interventional device and apply pressure to fix theadapter to the device. The adapter then is delivered with theinterventional device, and upon completion of the diagnostic ortherapeutic procedure, is used to retrieve the vascular filter.Alternatively, adapter 50 may be provided in a kit including a vascularfilter mounted on a guidewire (not shown).

[0046] Referring now to FIGS. 5A and 5B, a method of employing theadapter of FIGS. 4 to recover a vascular filter is described. In FIG.5A, vascular filter 30 of FIG. 3 is shown deployed along guidewire 38.After insertion of guidewire 38 and deployment of vascular filter 30,adapter 50 is mounted to the distal end of interventional device 60,illustratively an angioplasty catheter. Adapter 50 and angioplastycatheter 60 then are advanced along guidewire 38 to a location justproximal of, or in contact with, the vascular filter, where angioplastycatheter 60 is used to treat vascular disease. Inflation of the balloonof angioplasty catheter 60 causes emboli E to be liberated from thelesion, and be carried by the blood flow into filter 30.

[0047] With respect to FIG. 5B, after the interventional procedure iscompleted, the balloon of angioplasty catheter 60 is deflated andcatheter 60 is advanced distally along guidewire 38 to bring adapter 50into contact with filter 30. Filter 30 preferably is received withindistal end 51 of adapter 50 when the adapter is advanced further in thedistal direction. Alternatively, adapter 50 may receive at least aportion of filter 30 by retracting guidewire 38 proximally while holdingangioplasty catheter 60 and adapter 50 stationary.

[0048] The degree to which vascular filter 30 is enclosed within adapter50 may be varied depending on treatment requirements. This may beaccomplished by altering the size of adapter 50 or by controlling themovement of catheter 60 along guidewire 38. For example, in some casesit may be sufficient to enclose the mouth of filter 30 within adapter 50to facilitate retrieval. In such a situation, adapter 50 may beconstructed so that it is somewhat smaller than the length of filter 30,so only the mouth of the device fits into the adapter. In othersituations, however, it may be desired to enclose some or all of filter30 within adapter 50, and in such a case adapter 50 may be constructedso that it is somewhat larger than the length of vascular filter 30.

[0049] Referring now to FIG. 6, a retrieval catheter 70 constructed inaccordance with the principles of the present invention is described.Catheter 70 preferably includes tubular body 71, support wire 72,radiopaque marker 73 and opening 74. Body 71 and internal lumen 74preferably are constructed to a have a diameter sufficient toaccommodate an angioplasty catheter and a vascular filter such asdescribed hereinabove with respect to FIGS. 1-3.

[0050] Body 71 preferably is fabricated from a thin biocompatiblematerial, such as polyethylene, polypropylene, polyurethane, polyester,polyethylene terephthalate, nylon, polytetrafluoroethylene, polyimid, orPebax®. Body 71 also is sufficiently stiff to be advanced along aguidewire through curved vasculature, and to retrieve a vascular filter,without buckling or kinking. Retrieval catheter 70 may be maderadiopaque by using metal marker 73 or by constructing it of aradiopaque material such as a barium sulfate-infused (BaSO₄) polymer.

[0051] Retrieval catheter 70 may be mounted over a conventionalinterventional devices, such as an angioplasty catheter or stentdelivery system, prior to inserting the interventional device into thepatient's vasculature. For example, to mount retrieval catheter 70 on anangioplasty catheter, the distal end of the angioplasty catheter isinserted through distal end 75 of body 71, and the body then isretracted proximally on the angioplasty catheter until body 71 isdisposed proximally of the balloon of the angioplasty catheter, as shownin FIG. 7A. Such backloading of the retrieval catheter is requiredbecause the inflation port of a typical angioplasty catheter precludesmounting retrieval catheter 70 from the proximal end of the angioplastycatheter.

[0052] A first mode of using retrieval catheter 70 is now described withrespect to FIGS. 7A-7C. In FIG. 7A, an initial step of a treatmentprocedure is depicted, wherein vascular filter 30 is disposed at adistal end of guidewire 38, just distal of adapter 50, interventionaldevice 60, and retrieval catheter 70. Adapter 50 and retrieval catheter70 are mounted to interventional device 60 prior to insertion alongguidewire 38. After completion of the interventional procedure, theballoon of interventional device 60 is deflated, and the interventionaldevice is urged in the distal direction to cause adapter 50 to contactwith filter 30.

[0053] As shown in FIG. 7B, filter 30 may be received within the distalend 51 of adapter 50 when it is advanced further in the distaldirection. In particular, adapter 50 is advanced by movinginterventional device 60 along guidewire 38 so that it at leastpartially surrounds filter 30. Alternatively, adapter 50 may receive atleast a portion of filter 30 by retracting guidewire 38 in the proximaldirection while holding interventional device 60 stationary.

[0054] Next, as shown in FIG. 7C, retrieval catheter 70 is advanceddistally so that filter 30 and adapter 50 are received within lumen 74of retrieval catheter 70. In this manner it is possible to reduce therisk that the filter or adapter catches on other material, e.g., astent, deployed within the patient's vessel during removal.

[0055]FIGS. 8A and 8B depict an alternative mode of using retrievalcatheter 70 to retrieve a vascular filter without using adapter 50. InFIG. 8A, an initial step of a treatment procedure is depicted, whereinvascular filter 30 is disposed at a distal end of guidewire 38 followedby the balloon of an interventional device 60 and previously mountedretrieval catheter 70. After completing an interventional procedure, theballoon of interventional device 60 is deflated and advanced towardfilter 30.

[0056] As shown in FIG. 8B, retrieval catheter 70 is then advanceddistally so that the distal end of interventional device 60 and filter30 are received in lumen 74 of the retrieval catheter. In this manner,the risk that emboli will escape from filter 30 is reduced. In addition,because body 71 of retrieval catheter 70 completely encloses filter 30,the risk that a portion of the filter sac could become entangled with astent strut is also diminished. Alternatively, retrieval catheter 70 maybe held stationary, and filter 30 retracted in the proximal directioninto lumen 74.

[0057] In FIG. 9, an alternative embodiment of a retrieval adapterconstructed in accordance with the principles of the present inventionis described. Adapter 80 is substantially similar to retrieval adapter50 of FIGS. 4, except that tapered proximal end 81 is configured to abutagainst the distal end of interventional device 60, rather than tocouple together as shown in FIG. 5A.

[0058]FIGS. 10A and 10B depict another alternative embodiment of theapparatus of the present invention. Adapter 90 is substantially similarto adapter 50 of FIGS. 4, except that distal end 91 is not curved as inFIG. 4A, but instead includes a circular opening having a smooth,rounded edge. Lumen 92 preferably is of sufficient size to accommodateat least a portion of a deployed filter, thereby forming a close fitaround at least a portion of the mouth of the filter.

[0059]FIGS. 11A and 11B depict yet another alternative embodiment of theapparatus of the present invention. Adapter 100 is substantially similarto adapter 50 of FIGS. 4, except that distal end 101 is not curved as inFIG. 4A, but instead includes an oblique opening 102 into lumen 103.Opening 102 preferably includes a smooth, rounded edge. As for thepreviously-described embodiments, lumen 103 preferably is of sufficientsize to accommodate at least a portion of a deployed filter, and thusform a close fit around at least a portion of the mouth of the filter.

[0060] Each of adapters 50, 80, 90 and 100 may be coupled to (ordisposed adjacent to) the distal end of an interventional catheter sothat the adapter is delivered to a treatment site at the same time asthe working element (i.e., balloon or stent) of the interventionaldevice. Such concurrent delivery eliminates the steps of removing theinterventional device from the patient's vessel and inserting a separateretrieval sheath to the treatment site along the guidewire.

[0061] Referring now to FIG. 12, a further alternative embodiment of theapparatus of the present invention is described. In this embodiment,retrieval adapter 110 is similar in construction to retrieval adapter 50of FIGS. 4, except that adapter 110 is premounted on suspension strut 32of vascular filter 30. In particular, adapter 110 includes lumen 112 andtapered proximal region 114.

[0062] In operation, an interventional device may be advanced alongguidewire 38 until it abuts proximal end 114 of adapter 110, pushing theadapter distally along suspension strut 32 towards support hoop 31 offilter 30, until support hoop 31 is received within lumen 112. Theextent to which adapter 110 receives support hoop 31 may of course bedetermined by the length of adapter 110. Alternatively, adapter 110 maycollapse and retrieve vascular filter 30 by retracting guidewire 38 suchthat filter 30 is retracted proximally towards the adapter while holdingthe interventional device stationary.

[0063] FIGS. 13A-13C depict one method of using the apparatus of FIG.12. In FIG. 13A, during an initial step of an interventional procedure,filter 30 with pre-mounted retrieval adapter 110 is deployed in a vessel(not shown). A conventional interventional device 60, illustratively anangioplasty catheter, is then advanced along guidewire 38 until distalend 61 of the interventional device is disposed just proximal of, or incontact with, the proximal end of the adapter. Preferably, the adapteris positioned sufficiently far from the proximal end of the vascularfilter that small longitudinal movements of interventional device 60attendant upon use of that device do not cause distal end 61 to impingeagainst tapered proximal region 114 of adapter 110. It will of course berecognized that in some applications, e.g., where the vessel is short,some contact between the adapter and vascular filter can beaccommodated.

[0064] Interventional device 60 then is used to perform the desireddiagnostic or therapeutic treatment, during which emboli E may becomedislodged from the vessel wall. Those emboli travel with antegrade bloodflow and are captured in blood permeable sac 33 of filter 30. Aftercompletion of this procedure, the balloon of the interventional deviceis deflated and the interventional device is advanced along guidewire 38in the distal direction to bring distal end 61 of the interventionaldevice into abutment with tapered proximal region 114 of adapter 110, asshown in FIG. 13B.

[0065] With respect to FIG. 13C, continued advancement of interventionaldevice 60 in the distal direction causes support hoop 31 of filter 30 toat least partially enter lumen 112 of adapter 110, thereby causing thesupport hoop to close and closing the mouth of filter sac 33.Alternatively, adapter 110 may be caused to at least partially surroundsupport hoop 31 by retracting guidewire 38 proximally while holdinginterventional device 60 stationary.

[0066] The degree to which vascular filter 30 is captured in adapter 110depends on the length of lumen 112 within adapter 110 and also islimited by the length of the support hoop when folded over guidewire 38.Specifically, vascular filter 30 may be received within lumen 112 ofadapter 110 until the point on support hoop 31 opposite to theconnection to suspension strut 32 is urged against guidewire 38.

[0067] Because closing the vascular filter may prevent the vasculardevice from being re-deployed, it may be desirable to prevent theinadvertent closing of vascular filter 30. Such inadvertent closing maybe prevented by using a safety system deployed along guidewire 38, asshown in the embodiment of FIG. 14.

[0068] In FIG. 14, vascular filter 30 is disposed on guidewire 38 andincludes adapter 110 disposed on suspension strut 32 in the same manneras depicted in FIG. 12. In accordance with this aspect of the presentinvention, guidewire 38 includes safety system 120 comprising screw 122,nut 124 and stop 126. Preferably, these components are constructed of ahigh strength plastic or metal alloy, such as stainless steel.

[0069] Safety system 120 is intended to prevent an interventionaldevice, such as a balloon catheter or stent delivery system, fromaccidentally closing vascular filter 30. Screw 122 and stop 126preferably are fixed on guidewire 38, while nut 124 is configured tomove freely along guidewire 38 between screw 122 and stop 126. Stop 126restricts movement of nut 124 in the proximal direction, while screw 122selectively restricts movement of nut 124 in the distal direction.

[0070] Nut 124 may be advanced past screw 122 by rotating guidewire 38such that the threads of the screw mesh with the threads of the nut,thus advancing the nut over and past the screw until the nut is disposeddistally of the screw, i.e., between filter 30 and screw 122. When nut124 is disposed between screw 122 and stop 126, it prevents theinterventional device from advancing distally toward adapter 110 untilguidewire 38 is intentionally rotated. Once the intended diagnostic ortherapeutic procedure is completed, however, nut 124 is moved to aposition between filter 30 and screw 122 by rotating guidewire 38, andthen the interventional device may be advanced distally over stop 126and screw 122 to urge nut 124 into engagement with adapter 110, therebyclosing filter 30.

[0071] FIGS. 15A-15C depict a method of using the apparatus of FIG. 14.In FIG. 15A, during an initial step of an interventional procedure,filter 30 is deployed in a vessel (not shown) and includes adapter 110disposed on suspension strut 32, and safety system 120 disposed onguidewire 38. A conventional interventional device 60, illustratively anangioplasty catheter, is advanced along guidewire 38 and then used toeffect a desired diagnostic or therapeutic treatment, during whichemboli E may become dislodged from the vessel wall. Those emboli travelwith antegrade blood flow and are captured in blood permeable sac 33 offilter 30.

[0072] After completion of this procedure, the balloon of theinterventional device is deflated and the interventional device isadvanced along guidewire 38 in the distal direction and over stop 126until distal end 61 of the interventional device contacts nut 124. Thedistal end of interventional device 61 may push nut 124 until it is indirect contact with screw 122.

[0073] Next, as shown in FIG. 15B, nut 124 is advanced over and pastscrew 122 by rotating guidewire 38 so that the threads of nut 124 meshwith and advance over the threads of screw 122. Interventional device 60is then advanced distally over screw 122 to urge nut 124 into contactwith the proximal end of adapter 110. As shown in FIG. 15C, furtheradvancement of interventional device 60 in the distal direction causesnut 124 to urge adapter 110 distally, whereby support hoop 31 isreceived at least partially within lumen 112 of the adapter. In thismanner filter 30 may be collapsed for retrieval with little effort andwithout an additional equipment exchange or additional retrieval sheath.As for the previous embodiments, adapter 110 alternatively may be causedto at least partially surround support hoop 31 by retracting guidewire38 proximally while holding interventional device 60 stationary.

[0074] Although the present invention is illustratively described in thecontext of interventional devices such as angioplasty catheters andstent delivery systems, the apparatus of the present inventionadvantageously may be employed with atherectomy catheters, embolectomycatheters, vascular mapping catheters or any other suitable diagnosticor therapeutic interventional device, if desired.

[0075] Although preferred illustrative embodiments of the presentinvention are described above, it will be evident to one skilled in theart that various changes and modifications may be made without departingfrom the invention. It is intended in the appended claims to cover allsuch changes and modifications that fall within the true spirit andscope of the invention.

What is claimed is:
 1. Apparatus for use in conjunction with aninterventional device in retrieving a vascular filter disposed on aguidewire from a vessel, the apparatus comprising: a tubular body havinga proximal end, a distal end and a lumen, the tubular body configured tobe disposed on a distal region of the guidewire only so that theproximal end engages a distal end of the interventional device, thetubular body configured to receive at least a portion of the vascularfilter within the lumen during retrieval of the vascular filter from thevessel.
 2. The apparatus of claim 1 wherein the tubular body comprises abiocompatible material.
 3. The apparatus of claim 1 wherein the tubularbody comprises a radiopaque material.
 4. The apparatus of claim 3wherein the radiopaque material comprises a radiopaque coil embedded inthe tubular body.
 5. The apparatus of claim 1 wherein the proximal endis tapered to facilitate engagement with a distal end of theinterventional device.
 6. The apparatus of claim 5 wherein the tubularbody is mounted on the distal end of the interventional device.
 7. Theapparatus of claim 5 wherein the proximal end abuts against the distalend of the interventional device.
 8. The apparatus of claim 1 whereinthe distal end of the tubular body includes at least one slit.
 9. Theapparatus of claim 1 wherein the distal end of the tubular body isperforated.
 10. The apparatus of claim 1 wherein the tubular body has alength less than about 50 mm.
 11. A system for retrieving a vascularfilter comprising: a guidewire having a distal end; a vascular filterdisposed on the guidewire adjacent the distal end of the guidewire; aninterventional device having a distal end and a lumen extendingtherethrough, the interventional device disposed on the guidewireproximally of the vascular filter; and a retrieval adapter slidinglydisposed on the guidewire and interposed between the vascular filter andthe distal end of the interventional device.
 12. The system of claim 11wherein the retrieval adapter includes a lumen adapted to receive atleast a portion of the vascular filter.
 13. The system of claim 11wherein the retrieval adapter comprises a biocompatible material. 14.The system of claim 11 wherein the retrieval adapter comprises aradiopaque material.
 15. The system of claim 14 wherein the radiopaquematerial comprises a radiopaque coil embedded in the retrieval adapter.16. The system of claim 11 wherein the retrieval adapter furthercomprises a proximal region tapered to facilitate engagement with thedistal end of the interventional device.
 17. The system of claim 16wherein the retrieval adapter is configured to be mounted on the distalend of the interventional device.
 18. The system of claim 11 wherein adistal end of the retrieval adapter includes at least one slit.
 19. Thesystem of claim 11 wherein a distal end of the retrieval adapter isperforated.
 20. The system of claim 11 wherein the retrieval adapter hasa length of less than about 50 mm.
 21. A system for retrieving avascular filter comprising: a guidewire having a distal end; a vascularfilter disposed on the guidewire adjacent the distal end of theguidewire, the vascular filter comprising a suspension strut coupled tothe guidewire, a support hoop coupled to the suspension strut, and ablood permeable sac coupled to the support hoop; an interventionaldevice having a distal end and a lumen extending therethrough, theinterventional device disposed on the guidewire proximally of thevascular filter; and a retrieval adapter slidingly disposed on thesuspension strut.
 22. The system of claim 21 wherein the retrievaladapter includes a lumen adapted to receive at least a portion of thevascular filter.
 23. The system of claim 21 wherein the retrievaladapter comprises a biocompatible material.
 24. The system of claim 21wherein the retrieval adapter comprises a radiopaque material.
 25. Thesystem of claim 21 wherein a distal end of the retrieval adapter isradially expandable.
 26. The system of claim 21 further comprising asafety device that inhibits inadvertent closing of the vascular filter.27. A method of retrieving a vascular filter comprising: providing aguidewire, a vascular filter, an interventional device and a retrievaladapter; deploying the vascular filter on the guidewire distal to atreatment site; disposing a retrieval adapter on the guidewire inengagement with a distal end of the interventional device; advancing theretrieval adapter and interventional device along the guidewire to thetreatment site; performing a diagnostic or therapeutic procedure at thetreatment site using the interventional device; and upon completion ofthe diagnostic or therapeutic procedure, advancing the interventionaldevice distally along the guidewire so that the retrieval adaptercaptures the vascular filter.
 28. The method of claim 27 whereinadvancing the interventional device distally along the guidewire causesthe vascular filter to be received at least partially within a lumen ofthe retrieval adapter.
 29. A method of retrieving a vascular filtercomprising: providing a guidewire, a vascular filter including aretrieval adapter and an interventional device; deploying the vascularfilter and retrieval adapter on the guidewire distal to a treatmentsite; advancing the interventional device along the guidewire to thetreatment site; performing a diagnostic or therapeutic procedure at thetreatment site using the interventional device; upon completion of thediagnostic or therapeutic procedure, advancing the interventional devicedistally along the guidewire so that the interventional device abutsagainst the retrieval adapter; and advancing the interventional devicefurther distally along the guidewire so that the interventional devicecauses the retrieval adapter to capture the vascular filter.
 30. Themethod of claim 29 wherein advancing the interventional device distallyalong the guidewire causes the vascular filter to be received at leastpartially within a lumen of the retrieval adapter.